| Urban Green spaces are playing an important role in mitigating environmental issues from urbanization as a key component of urban ecosystem in recent years. Within the intensified urbanization process, the urban ecological problems have become increasingly protruding. The virtuous cycle of urban green ecosystem and the sustainable development of coexistence with nature have been greatly challenged. The soil C, N, P element is the key factor of the ecological structure and function. Understanding the cycle process of urban green space ecosystem C, N, P, element in the background of urbanization has important theoretical significance for the scientific management and regulation of urban green space ecosystem. This study selected along the "Urban-Suburb-Rural" ecological interfaces for research sample plots in Nanchang, and choice of three different types of vegetation (forest, shrub, lawn) to study. Through combination survey and cultivation, we research the variation characteristics of soil N、P supply and C stability along Urban-rural green in different vegetation types. At the same time we use the method of xenobiotic added to research the P element coupling mechanism with C, N, for provide theoretical guidance for the scientific management of urban green space and sustainable development. The main results are as follows:(1) In the urban-rural gradient, soil organic carbon, total nitrogen, total phosphorus, pH, microbial biomass carbon, microbial biomass nitrogen, nitrate nitrogen and phosphorus showed for urban>suburb>rural, it is show urban development have the significant effect on soil physical and chemical properties. In addition to soil nitrate nitrogen and total mineral nitrogen showed the tendency of forest> shrub> lawn, other soil physical and chemical parameters were not significantly different in the vegetation types, indicating soil properties affected by greater urban development.(2) The soil carbon mineralization rates change along urban-rural gradient, vegetation type and culture temperature. Soil carbon mineralization rate have shown a significant positive correlation with soil carbon and soil pH, total nitrogen, total phosphorus, available phosphorus, MBC, MBN. The soil carbon mineralization rates in urban-rural gradient showed urban>suburb>rural, whether in training early, middle and late, indicating urban development increased content of labile organic carbon, and plays a positive feedback effect in soil soil carbon mineralization. Soil carbon in vegetation types showed lawn> forest> shrub, it showed the soil of forest and shrub more favorable fixed carbon compared to lawn soil.(3) Nitrification rates and P mineralization rate have significant changes along urban-rural gradient; and Nitrification rate showed urban>suburb>rural, the values were 3.14±1.02 mg N kg-1 soil 30 d-1,-1.05±0.64 and 0.87±0.55 mg N kg-1 soil 30 d-1.Soil P mineralization rate showed urban>suburb>rural, Show urban development play a positive feedback in the circulation of soil N, P. Different vegetation types have significant effect in nitrogen mineralization and P mineralization rate, in the different vegetation types soil mineral nitrogen showed lawn(15.99± 1.15 mg N kg-1 soil 30 d-1fores(11.48±1.14 mg N kg-1 soil 30 d-1)>shrub(11.41±1.21 mg N kg-1 soil 30 d-1); and the soil P mineralization rate showed forest(86.21 ±20.43 mg P kg-1 soil 30 d-l)> shrub(38.43± 16.33 mg P kg-1 soil 30 d-1)> lawn(-13.58±5.21 mg P kg-1 soil 30 d"1). Compared with the lawn, the forest and shrub soil limited in N, and less susceptible to P restrictions.In conclusion, urbanization altered soil N and P transformation and organic C stability in vegetations along urban-rural gradient. We also found the interaction among N, P and C cyclings in vegetation soils along urban-rural gradient, but their interative mechanism need be further studied. |
PDF Full Text Request